Mysterious Power Line Super Gremlins

DarqueKnight

Mysterious Power Line Super Gremlins
Subtitle: My Wonderful Day With The Power Company

Introduction

On Monday 1/26/09, I noticed some graininess at the sides and rear of the sound stage in my two channel system. I also noticed an apparent decrease in sound level and bass slam. The first thing I checked was the Power Port Premier AC regenerator. Sometimes, if the PPP sees something on the power line it doesn't like, like a huge transient, it will disconnect the regenerator circuit and the PPP has to be manually reset. The PPP was functioning normally. However, when I switched the display to show incoming total harmonic distortion, it read a whopping 7.7%! THD is normally in the area of 2%. I connected an oscilloscope to the right amplifier's AC receptacle and saw a grossly distorted waveform. This distortion persisted throughout the week and I took the following pictures Thursday evening and sent them to the power company.


Figure 1. Distorted power sine wave form measured 1/29/09.


Figure 2. FFT of residential power measured 1/29/09.

---

Sent: Thu 1/29/2009 9:43 PM
To: w@entergy.com
Subject: Residential Power Line Noise

Mr. W,

I monitor my home's power line quality due to the sensitive electronic home entertainment equipment I own.

This week I noticed a substantial increase in the harmonic distortion of the power delivered to my home. Please see the attached oscilloscope traces for the sine waveform and the Fast Fourier Transform of the wall voltage.

The sine wave shows near a high degree of flattening of the peaks and gross deformations of the waveform sides. I don't recall seeing this level of waveform distortion during my entire time in my current residence (over 6.5 years).

The 3rd, 5th, and 7th harmonics show amplitudes of 41 dB, 42 dB, and 23 dB respectively. The total harmonic distortion was 7.7%. On January 10, 2009, the 3rd, 5th, and 7th harmonics had amplitudes of 34 dB, 34 dB, and 23 dB respectively. The total harmonic distortion was 2.4%.

I would like to know the reason for the dramatic decrease in my power quality. If you are not the right person to address my inquiry, I apologize for the inconvenience and ask that you forward it to the appropriate person.

To avoid initiating "phone tag", I would prefer a response by email.

Thank you for your assistance.

---

I assumed I would hear back from the power company in a few days...maybe
a week or so. To my surprise, I received a reply the next morning:

---

From: c@entergy.com
Sent: Fri 1/30/2009 8:00 AM
Cc: w@entergy.com; m@entergy.com; f@entergy.com
Subject: RE: Residential Power Line Noise

Dr. S.,

I am the Asset Planning Manager for Louisiana. I would like to have a service request generated so a serviceman can come by your residence and check all connections from the common point of coupling (the meter) to the transformer serving the residence. If he finds anything, he will make the necessary repairs and we will notify you of the cause. If he can not find anything that will explain the phenomena, we will have a monitor installed for a period of time to see if we can pin point where the harmonics is coming from. If the monitoring is necessary, I will have one of my Planning Engineers set up the monitor, analyze the data, and let you know what we found. In order to get the process rolling, I will need you to call 1(800)ENTERGY or 1(800)368-3749 from your home phone or from any phone if you have your account number and tell them you are having voltage issues. They will create the appropriate service request and a Serviceman will be scheduled. I have copied the Baton Rouge Planning Engineer and Baton Rouge Service Supervisor so they can be looking for the service request. In the mean time, can you reply back with the address where you are experiencing the Power Quality issues.

---

I called the customer service department at 9 am and I was shocked again to hear that they would have a technician at my home within two hours. Not two days or two weeks, but two hours.

The technician arrived at my home at 10:22 am. This is where the fun begins. I waited ten minutes and then joined the technician at my power meter where he was taking measurements.

Tech: Man, I can't find anything wrong. I don't know why they sent me out here. Your voltage is fine. Your current is fine. What kinda problems are you having?

Me: I am seeing higher than normal noise and distortion on the power line.

Tech: (Somewhat agitated now) How are you seeing that? Is everything working inside? Nobody else out in this area is complaining.

Me: Everything is "working" but not as well as it was before the higher distortion appeared.

Tech: What do you mean not working as well? Like I said, nobody else is complaining.

Me: It would be difficult to explain out here. If you come inside I can show you some measurement plots and provide a better explanation.

Tech: I don't need to come inside and I already saw that stuff you sent in that email. None of that has anything to do with what I'm reading out here. I really don't understand why they got me out here 'cause ain't nothin' wrong. This is just wasting my time.

Me: Well, you can just stay out here and be bewildered or you can come inside and get the full explanation or you can just leave. Either one is fine with me.

Tech: Alright. I'll see whatcha got, but nothing on the inside of your house has anything to do with what's goin' on out here.

Once inside, I had some difficulty keeping the tech's attention focused on my oscilloscope's and television's screens rather than my decor. It would never have occurred to me that a power company technician would have such a high degree of interest in interior design.

I had the plasma TV in my home theater system on and plugged into the wall rather than the Power Plant Premier. The tech complimented me on the nice picture I had. Then I unplugged the TV from the wall and plugged it into the PPP and the improvement was immediately obvious. Next, I displayed the sine wave and FFT traces from the wall and PPP and discussed the differences between them. I also discussed printouts of previous wall power plots when the power was in spec. I explained that the difference in the picture quality he saw was due to the amount of noise and distortion in the power. This is the basis of my complaint. I further explained that higher noise and distortion also made a difference in the way my stereo system sounded.

Tech: (No longer visible agitated now) You must be an engineer.

Mr: Yes, I am an electrical engineer.

Tech: I don't know much about harmonics and distortion. That's something the engineers talk about. I can call my supervisor and let you speak to him.

Further compounding my shocks (no pun intended) was the supervisor's initiation of a discussion of the effects of power line noise on high end electronics. He suggested that I get a power line conditioner. I explained that I already had four such devices but that some of my equipment must be connected directly to the wall.

I then asked if their system noise specification had changed and if the higher levels of noise and distortion were going to be the norm going forward. He said he didn't know what the system specification was and that he would have a power quality engineer contact me. He also said that one or more of my neighbors might be the cause of the distortion or it could be a nearby business. Whatever the cause, he said the power company could install monitoring equipment to trace the cause.

DarqueKnight

After the supervisor hung up. The tech and I had another brief discussion about home furnishings
and interior design and I bid him farewell. I then sent the following email to the power company:

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Subject: Technician Inspection Results
Date: Fri, 30 Jan 2009 11:10 AM
To: c@entergy.com
Cc: w@entergy.com, m@entergy.com, f@entergy.com

Mr. C,

An Entergy service technician, Mr. P, inspected my power service this morning and found nothing out of the ordinary which would explain the recent significant increase in harmonic distortion on my power lines (from typical 2% to now over 7%). I was able to speak to a a service supervisor, Mr. F, duing the technician's visit and Mr. F informed me that the problem may be caused by devices used by another nearby customer. Mr. F further advised me that the higher harmonic distortion I am measuring in the range of 7% may be within Entergy's system specification, but he did not know for sure. He suggested that a power quality engineer review my measurements and get back to me.

---

I received the following email from a power quality engineer later that day:

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From: m@entergy.com
Sent: Fri 1/30/2009 3:36 PM
Cc: f@entergy.com; [email]c@entergy.com
Subject: RE: Technician Inspection Results

Dr. S.,

I will work with F to install a PQ monitor on your residence service. I’ll check on the availability of the monitors and get back with you on Monday.

Have a good weekend.
[/email]

---

I took measurements the next day, Saturday, Jan. 31, 2009 and everything was back to normal:


Figure 3. Power sine waveform measured 1/31/09.


Figure 4. Power FFT plot measured 1/31/09.

Everything remained normal all weekend. If the ugliness returned on Monday morning, then I would have suspected a Monday-Friday commercial customer as the culprit. I like a good mystery, but not when it's a mysterious source of noise pollution on the power lines feeding my audio and video gear.:mad:

On the following Monday morning, I sent an email to the power company informing them that my power was back to normal:

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Sent: Monday, February 02, 2009 11:08 AM
To: m@entergy.com
Cc: w@entergy.com; c@entergy.com; f@entergy.com

Subject: Power Quality Now Back To Normal

Mr. M,

When I took measurements on Saturday, Jan. 31st, the readings were back to normal with a sinusoidal waveform and total harmonic distortion in the area of 2%. I took readings again this morning and my power quality is still normal. I am attaching screen shots of my oscilloscope measurements from 5:35 pm Jan. 31st.

The fact that the higher distortion I measured during Monday-Friday of last week indicates that it might have been caused by a commercial customer. There also may have been some maintenance or repair operation by Entergy that caused the anomaly, since the high distortion readings were evident whether I took measurements during the day, night or early morning hours.

---

Sent: Mon 2/2/2009 11:27 AM
Cc: w@entergy.com; c@entergy.com; f@entergy.com
Subject: RE: Power Quality Now Back To Normal

Dr. S.,

I agree that the issue was most likely an isolated event. We rarely see PQ issues on single phase services.

If you are satisfied with this outcome, we can go ahead and cancel installing a PQ monitor on your residence.

Please let C or I know if you see any distortions for a long period of time.

Again let me know if you have any questions or concerns.

---

Sent: Mon 2/2/2009 12:17 PM
To: m@entergy.com
Cc: w@entergy.com; c@entergy.com; f@entergy.com
Subject: RE: Power Quality Now Back To Normal

Mr. M.,

You can go ahead and cancel the PQ monitoring request at my residence. I will let you know if I see another long lasting PQ anomaly. Thank you and your colleagues for your prompt assistance.

---

I have not had any further problems with power line quality.

One important thing I have learned from all this is that neighborhoods served by underground power lines usually have less than the optimum number of transformers and therefore a less than optimum level of noise isolation. This is because the developers of such neighborhoods typically balk at the larger number of transformers strictly for aesthetic reasons.

For the next house, I'll check into the cost of a dedicated residential transformer.:)

Early B.

Hmmm.... you're an electrical engineer and an audiophile? That's a dangerous combination. It's gotta drive you nuts.

DarqueKnight

The two compliment each other very well. Why would you think otherwise?

Polkersince85

Excellent research.

Using an oscilloscope and a test tone record is a good way to set up the cartridge on the turntable also. Gets it right in the middle of the groove.

Early B.

DarqueKnight wrote: »

The two compliment each other very well. Why would you think otherwise?

Precisely. Only an EE would ask such a question.:p

disneyjoe7

Well from the scope picture of sine wave, I say What the ....! Ok is this noise from your house or what? I would kill everything all the breaks fuse except one for you scope, it would test if the noise is from something in the house vs. something going to house.

Good Luck.

Dennis Gardner

I bet he narrows it down to the HIDs in his neighbor's basement or the clothesline Tesla coil experiment from the science project geek across the street.:D

There is no doubt that the electric company has his residence marked as "customer from hell" in the notes on account.;)

organ

That is hardcore. I bet you're the first person they've gotten a complaint from about the "quality" of their power. It's nice to see you do something about it.
There's a chance that one of your neighbours got a new toy or appliance that's sending nasty harmonics back to the power lines.
Do you know any technicians who could build you a custom line conditioner for that particular problem? I"m sure the right transformer and caps should filter it out. Maybe the commercial line conditioners are cleaning different harmonics and completely ignoring the one you're receiving.

DarqueKnight

disneyjoe7 wrote: »

I would kill everything all the breaks fuse except one for you scope, it would test if the noise is from something in the house vs. something going to house.

organ wrote: »

There's a chance that one of your neighbours got a new toy or appliance that's sending nasty harmonics back to the power lines.

There is nothing in a residence that would cause triple the normal amount of harmonic distortion to appear on a neighbors power line. The fact that the the 3rd and 5th harmonics were increased to over twice their normal amplitude indicates that the problem originated with the power company or with a commercial customer.

organ wrote: »

Do you know any technicians who could build you a custom line conditioner for that particular problem? I"m sure the right transformer and caps should filter it out.

No. Not noise of this magnitude. There was something fundamentally wrong with the power coming off the utility grid to the extent that the waveform was no longer sinusoidal in shape.

I left home Friday afternoon and did not return until Saturday afternoon. The problem was corrected sometime within that 24 hour period. I suspect it was corrected late Friday afternoon or early Friday evening.

I have an idea about the cause of the problem due to the nature of the oscilloscope plots and how quickly the problem was resolved after I formally complained, but I don't care to publicly speculate.

treitz3

organ wrote: »

That is hardcore. I bet you're the first person they've gotten a complaint from about the "quality" of their power. It's nice to see you do something about it.

Maybe in his neighborhood. I've complained many a time about the quality of the power in my neighborhood and I have just come to the conclusion that I need a dedicated residential transformer. The electric company will not pay for one and since I live in a town home, even if I did, it would not be approved by the HOA board.

I'm stuck with **** for power until I move and that's the fact Jack! :mad:

skrol

DarqueKnight, where do you practice your EE craft besides your home (ie. profession)? I have enjoyed your home power and power conditioning threads and am inspired. I recently added a power conditioner to my system and am amazed and puzzled at the improvement (psychological?). There seems to be much discussion concerning the effectiveness of conditioners on SQ. I suspect that it may be dependent on the quality of the component power supplies. I am planning to take some measurements of the wall power, conditioned power and component power supply output (with and without the conditioner) to see if the benefit is real and measurable.

What scope are you using? I just have an old Tektronics scope (T922) but I'll stick a digi-cam in front for data capture.

Stan

DarqueKnight

skrol wrote: »

DarqueKnight, where do you practice your EE craft besides your home (ie. profession)?

I have a private engineering consulting practice and I occasionally teach a class or two in electrical engineering.

skrol wrote: »

I recently added a power conditioner to my system and am amazed and puzzled at the improvement (psychological?). There seems to be much discussion concerning the effectiveness of conditioners on SQ. I suspect that it may be dependent on the quality of the component power supplies.

The degree of improvement you hear, if any, will depend on a lot of factors such as the resolution capability of your components and cabling, the quality of power you receive from the power company, the quality of the component power supplies and the environmental electromagnetic background noise.

skrol wrote: »

I am planning to take some measurements of the wall power, conditioned power and component power supply output (with and without the conditioner) to see if the benefit is real and measurable.

Let us know what you find out.:)

skrol wrote: »

What scope are you using? I just have an old Tektronics scope (T922) but I'll stick a digi-cam in front for data capture.

I'm using a Tektronix TDS 2012. A communications module is available for it to enable the capture of data and screen shots. Lugging a laptop around with the scope is just as cumbersome as lugging around a camera, so I haven't invested in a com module (yet).

reeltrouble1

I always find interesting the group which makes a change, then hears somethings better and then needs to qualify the results with a measurement, when you hear something that sounds worse do you do this? Or only when you hear something better?

RT1

TNRabbit

DarqueKnight, that was AWESOME~

treitz3

RT1, I rely on my ears. That's the only thing that tells me the truth, and there's not much truth in audio.

DarqueKnight

reeltrouble1 wrote: »

I always find interesting the group which makes a change, then hears somethings better and then needs to qualify the results with a measurement...

Well, there is that pesky placebo effect.

reeltrouble1 wrote: »

...when you hear something that sounds worse do you do this? Or only when you hear something better?

Worse results and no change results are in line with "conventional wisdom" and thus no further validation is required or expected.;)

reeltrouble1

DarqueKnight wrote: »

Well, there is that pesky placebo effect.

Yes, well I suspect at least for myself the pesky placebo has been run-off by a recusant reality. It either is better or it is not better, these are the only two possibilities.

The placebo lies somewhere between the realms of the mind's confusion of actuality and reality. Both of which are known to be Reel in the Rabbit Hole of Audio.

Were it not for wonderment their would be no science.

Still, the acutal activity of the measurement with a physical electronic device is common enough amongst audiophiles to at least hypothysize the individual brain is somehow hard-wired and you are placed into your group without choice, although still with free will, the need to test is likely overwhelming or underwhelming.

RT1

Systems

reeltrouble1 wrote: »

Yes, well I suspect at least for myself the pesky placebo has been run-off by a recusant reality. It either is better or it is not better, these are the only two possibilities.

The placebo lies somewhere between the realms of the mind's confusion of actuality and reality. Both of which are known to be Reel in the Rabbit Hole of Audio.

Were it not for wonderment their would be no science.

Still, the acutal activity of the measurement with a physical electronic device is common enough amongst audiophiles to at least hypothysize the individual brain is somehow hard-wired and you are placed into your group without choice, although still with free will, the need to test is likely overwhelming or underwhelming.

RT1

Thanks, I needed a haircut:)

treitz3

DarqueKnight wrote: »

On Monday....I noticed some graininess at the sides and rear of the sound stage in my two channel system. I also noticed an apparent decrease in sound level and bass slam.

Hmmm, you mean to tell me that he noticed this without a measurement? Say it ain't so. :eek:

Simply amazing. I wonder how he did it. :rolleyes:

reeltrouble1

Lorthos wrote: »

Thanks, I needed a haircut:)

You are welcome, did you notice the King of Spades holding the Barber Pole due north, well, magnetic north as we must always account for the placebo within some degree of variation.

RT1

reeltrouble1

treitz3 wrote: »

Hmmm, you mean to tell me that he noticed this without a measurement? Say it ain't so. :eek:

Simply amazing. I wonder how he did it. :rolleyes:

There is nothing wrong with the man's hearing, I think it is likely exceptional.

RT1

DarqueKnight

reeltrouble1 wrote: »

...the need to test is likely overwhelming or underwhelming.

Many of us just like playing with meters...even to the point of preferring gear that has meters on the faceplate.

However, I'll bet few will admit to such.

treitz3

I was being sarcastic. Very sarcastic. I know the "others" are watching.

reeltrouble1

DarqueKnight wrote: »

Many of us just like playing with meters... I'll bet few will admit to such.

Likely true. The way you break it down, what appears to be such an interesting group to me is now rather, well, rather limited in overall scope (get it, scope:)), however, I just had a thought.









Q, What happens when a boy meter player meets a girl meter player???



A. Sparks Fly!!!!!!!!!!!:D


RT1

skrol

reeltrouble1 wrote: »

I always find interesting the group which makes a change, then hears somethings better and then needs to qualify the results with a measurement, when you hear something that sounds worse do you do this? Or only when you hear something better?

RT1

It is just have to prove to myself that it is not all in my head. Yes, it is the engineer thing in me that thinks its just plain fun. Plus, I have this dag-gone test equipment sitting in my basement that I need to justify keeping. ... Anyone interested in a flutter meter?
Stan

hearingimpared

Doc,

This thread has been one of the most interesting reads I've come across. Your engineering skills as well as your writing skills are just extremely impressive.

I find it hard to read (I have ADHS) and find it hard to stay focused when reading but your writings are so interesting that I just seem to get sucked into your world.

hearingimpared

The kicker here is that when I met you at Polkfest I found you to be a regular guy not some geek with tape on his glasses.:D;)

Polkersince85

hearingimpared wrote: »

The kicker here is that when I met you at Polkfest I found you to be a regular guy not some geek with tape on his glasses.:D;)

You didn't notice the slide rule sheath on his belt?

organ

Ouch! That must have been really bad. Good to hear that they fixed the problem. Enjoy the tunes!

Treitz,
Did you try a commercial line conditioner?

DarqueKnight

hearingimpared wrote: »

The kicker here is that when I met you at Polkfest I found you to be a regular guy not some geek with tape on his glasses.:D;)

I have my little eccentricities. They're just not the stereotypical geekish type.;)